1. Field of the Invention
This invention relates to a cylinder gauge for measuring a diameter of a hole or the like of a workpiece.
2. Description of the Prior Art
A head portion housing therein a measuring element and the like in the conventional cylinder gauge is of such arrangement as shown in FIG. 1. More specifically, in the drawing, an anvil 2 is detachably mounted to one end (to the left in the drawing) of a head 1 through a box nut 3, and a measuring element 4 is slidably provided at the other end of this head 1. Coupled onto this measuring element 4 is a compression coil spring 5, which constantly biases the measuring element 4 into the head 1. The head 1 is slidably provided at the other end thereof with a guide member 6 for causing the measuring element 4 to abut against the inner wall surface of the workpiece, not shown, in its vertical state. Confined between this guide member 6 and the head 1 is a compression coil spring 7, which constantly biases the guide member 6 outwardly from the head 1, and the guide member 6 is stopped by a stopper 1A integrally, threadably coupled into the head 1. Further, the inner end of the measuring element 4 is abutted against one end of a spindle 9 through an L-shaped cam 8 whose central portion is rotatably supported by the head 1, whereby an axial movement of the spindle 9 is imparted to the measuring element 4 as its movement in the radial direction of the spindle 9. The other end of this spindle 9 is connected to an indicating device such as a dial gauge, not shown, and the spindle 9 is axially, movably incorporated in a cylinder body 1B.
As described above, in the cylinder gauge having the conventional construction, two springs 5 and 7 as being the biasing means are provided around the measuring element 4, a substantially cylinder-shaped guide member 6 is provided, and further, in order to connect the spindle 9 to the measuring element 4 through a cam 8 or a link, not shown, large sizes and forms are needed for the head 1 and the guide member 6, both of which are centered about the axis of the measuring element 4, and, even if limitation is imposed on the design, the distance between the axis of the measuring element 4 and the bottom end, in the drawing, of the guide member 6 comes to be about 10 mm. In consequence, in measuring a diameter of the bottom of a shallow hole, blind hole or the like, there has been presented such a disadvantage that the diameter of a portion spaced apart about 10 mm or less from the bottom of the hole, blind hole or the like, because the bottom end, in the drawing, of the guide member 6 abuts against the bottom of the hole.